Canthiswork......yes it can, or atleast i think it can.
I'm the husband in the same/similar situation. Originally my wife and I had made it all about a primary/secondary relationship and we retained some veto power over the other. We've now let go of that definition realising that use of it would break the other's hearts. I'm in love with my girlfriend as much as i am with my wife, but differently. I hold back with my girlfriend because although she loves me too i'm not really sure of her intentions in life. We'll always be friends that is a given, i'll allow her to find her own relationship however she see fits but she hasn't expressed that she wants anything more.
We're still pretty new so it'll take some time but i could see us coming out to the world if that was required. I would love to meet her mother and be known as her boyfriend. I could even see having some sort of non-official wedding ceremony, comingling finances, owning property together....but i will wait an appropriate amount of time. I didn't marry my wife for several years so i would expect to take no less time with her. Lots of discussions would need to be had but i think everyone can be happy.
For now i just enjoy what we have and try to keep making it work. Hopefully it always will but she told me once that she was a little too greedy
and wanted one of me all to herself. Since i can't offer that i don't expect her to stay around for ever as a lover. But one can hope she'll be okay with what i can offer.